Post-impact dynamics of droplet on bare stranded overhead power transmission lines with varying surface properties

Overhead transmission lines are the most key component in power transmission systems, the bare transmission lines with stranded conductors are the main type for long-range power transmission. However, the long range makes the transmission lines easily be affected by rain icing problem in winter or cold regions, therefore the understandings of how the rain droplet interacting with surfaces of this kind of transmission lines are significant. By using many-body dissipative particle dynamics, the present work simulates the droplet impact on the stranded conductors with varying surface properties, such as surface wettability, number of strands, and twist pitch. The simulation results show that hydrophilic surfaces can retain most of the liquid while the super hydrophobic ones can repel most liquid after impact. A large number of strands, which means a large size of grooves, will force the liquid to flow along the grooves after impact. In this circumstance, grooves on surfaces with short twist pitch can guide the liquid to flow to a more downward direction, while grooves on surfaces with long twist pitch can guide the liquid flow closer to the axial direction of the transmission line and retain more liquid on the surface after impact. Besides, for bouncing cases, longer twist pitch can cause longer contact time.